[PATCH v2 2/5] scsi: BusLogic: Avoid unbounded `vsprintf' use

From: Maciej W. Rozycki
Date: Tue Apr 20 2021 - 14:01:56 EST


Existing `blogic_msg' invocations do not appear to overrun its internal
buffer of a fixed length of 100, which would cause stack corruption, but
it's easy to miss with possible further updates and a fix is cheap in
performance terms, so limit the output produced into the buffer by using
`vscnprintf' rather than `vsprintf'.

Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxxx>
---
Changes from v1:

- use `vscnprintf' instead of `vsnprintf' for the correct character count.
---
drivers/scsi/BusLogic.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

linux-buslogic-vscnprintf.diff
Index: linux-macro-ide/drivers/scsi/BusLogic.c
===================================================================
--- linux-macro-ide.orig/drivers/scsi/BusLogic.c
+++ linux-macro-ide/drivers/scsi/BusLogic.c
@@ -3588,7 +3588,7 @@ static void blogic_msg(enum blogic_msgle
int len = 0;

va_start(args, adapter);
- len = vsprintf(buf, fmt, args);
+ len = vscnprintf(buf, sizeof(buf), fmt, args);
va_end(args);
if (msglevel == BLOGIC_ANNOUNCE_LEVEL) {
static int msglines = 0;